The TMZ/XL765 combination decreases serum GH and PRL of mice bearing GH3 xenografts. A and B, After treatment with DMSO, TMZ, XL765, or the XL765/TMZ combination, the blood of the nude mice xenograft with GH3 tumor was collected and serum rat-GH and rat-PRL were measured by IRMA (TMZ/XL765 combination vs TMZ or XL765 alone: ***P <.001).

XL765 is active against class I PI3K (IC50 = 39, 113, 9 and 43 nM for p110α, β, γ and δ, respectively). XL765 also inhibits DNA-PK (IC50 = 150 nM) and mTOR (IC50 = 157 nM) but not XL-147 which shows IC50 values of > 15 μM. [1] XL765 treatment results in decreased cell viability in 13 PDA cell lines in a dose-dependent manner. XL765, a dual-target PI3K/mTOR inhibitor, inhibits cell growth and apoptosis in many more cell lines and at lower concentrations as compared to the PI3K-selective inhibitors XL147 and PIK90. The effect can be recapitulated by using combinations of single-targeted compounds. XL765 significantly reduces phosphorylation of the mTOR targets S6, S6K, and 4EBP1, which is associated with greater apoptosis induction rather than to PI3K inhibition alone. XL765 treatment causes accumulation of autophagosomes in MIAPaCa-2 cells, and results in significant dose-dependent AVO induction and LC3-II stimulation in MIAPaCa-2 cells stably expressing a LC3-GFP construct. [2]

In vivo

The combination of XL765 (30 mg/kg) with chloroquine (50 mg/kg) results in significant inhibition of BxPC-3 xenograft growth in mice models, while XL765 alone at the same dose has no inhibitory effect. [2] Oral administration of XL765 results in greater than 12-fold reduction in median tumor bioluminescence compared to control and improvement in median survival in nude mice implanted intracranially with GBM 39-luc cells. XL765 in combination with temozolomide (TMZ) yields a 140-fold reduction in median bioluminescence with a trend toward improvement in median survival compared with TMZ alone. [3]

Cells are treated with XL765 24 hours after plating and harvested for apoptosis or autophagy assays at 24, 48, or 72 hours after XL765 treatment. Apoptosis is determined by total percentage of annexin V-positive cells by fluorescence-activated cell sorting (FACS). Acidic vesicular organelles (AVOs) are detected in XL765-treated cells by vital staining with acridine orange. The degree of AVO formation is expressed as fold increase of acridine orange fluorescence intensity (FL3) in XL765-treated cells versus control cells.

Animal Study:

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

Species

Mouse

Rat

Rabbit

Guinea pig

Hamster

Dog

Weight (kg)

0.02

0.15

1.8

0.4

0.08

10

Body Surface Area (m2)

0.007

0.025

0.15

0.05

0.02

0.5

Km factor

3

6

12

8

5

20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by

Animal B Km

Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the Km factor for a mouse and then divide by the Km factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.

* <1 mg/ml means slightly soluble or insoluble.* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

LY294002 is the first synthetic molecule known to inhibit PI3Kα/δ/β with IC50 of 0.5 μM/0.57 μM/0.97 μM in cell-free assays, respectively; more stable in solution than Wortmannin, and also blocks autophagosome formation.

3-Methyladenine (3-MA) is a selective PI3K inhibitor for Vps34 and PI3Kγ with IC50 of 25 μM and 60 μM in HeLa cells; blocks class I PI3K consistently, whereas suppression of class III PI3K is transient, and also blocks autophagosome formation.

CAL-101 (Idelalisib, GS-1101) is a selective p110δ inhibitor with IC50 of 2.5 nM in cell-free assays; shown to have 40- to 300-fold greater selectivity for p110δ than p110α/β/γ, and 400- to 4000-fold more selectivity to p110δ than C2β, hVPS34, DNA-PK and mTOR.

Wortmannin is the first described PI3K inhibitor with IC50 of 3 nM in a cell-free assay, with little selectivity within the PI3K family. Also blocks autophagosome formation and potently inhibits DNA-PK/ATM with IC50 of 16 nM and 150 nM in cell-free assays.